3- and 4-Arm Star Polymers (PEG3 and PEG4) via Metal-Free Azide-Alkyne Click Reaction

Star polymers are known for their different structural and functional properties. Depending on their structure, they may display a wide range of characteristics. Star polymers can be synthesized using either a core-first or arm-first strategy. Numerous synthetic approaches can be used in both cases. In this work, 3- and 4-arm star polymers were prepared via the metal-free azide-alkyne click reaction. Trifunctional and tetrafunctional propiolate (acetylenecarboxylate) ester-containing cores were prepared and then subjected to a metal-free azide-alkyne reaction with azide end-functionalized PEG (PEG-N3) to yield A3 and A4-type star polymers, respectively. All the structures were characterized using 1H and 13C NMR spectroscopy and GPC.